#include<bits/stdc++.h>

using namespace std;

using int64 = long long;

int main()
{
  int N, M;
  bool deg[500] = {};

  cin >> N >> M;
  for(int i = 0; i < M; i++) {
    int a, b;
    cin >> a >> b;
    deg[a] ^= 1;
    deg[b] ^= 1;
  }

  auto p = count(deg, deg + 500, true);
  if(p == 2 || p == 0) {
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
}